A mobile device typically provides a plurality of modes of operation. In one mode it typically handles active transmission and reception implying high power consumption, while the so called deep sleep (Dormant State) mode is putting the mobile device in a lower power state only allowing discontinuous reception. The low power consumption of the dormant state is typically implemented by disabling a big portion of the processing components of the mobile device, disabling a high frequency clock (providing a clock signal in the order of MHz) and only allowing a power efficient low frequency clock (providing a clock signal in the order of kHz) to trigger a wake up of the system, i.e. the disabled components, after a certain amount of time. For this, the low frequency clock needs to have a certain accuracy and known timing relation to the high frequency clock to ensure that the wakeup of the system is done at a known accurate position in time. Otherwise, for example, the synchronization to the network might be lost or the device needs enhanced search capabilities for cell reacquisition. Accordingly, accurate and efficient approaches that allow determining the relation between the low frequency clock and the high frequency clock are desirable.